Many electronic devices can include a sensor to detect rotational input. For example, an electronic device can include a rotary encoder to determine the angular velocity of a rotatable component associated with the electronic device. Conventional rotary encoders can include a light source and an optical sensor.
The light source can illuminate a portion of a patterned surface of the rotatable component. The optical sensor can collect light reflected by the patterned surface and generate electrical signals corresponding to the collected light, which then can be conveyed to the electronic device. The electronic device can analyze the received electrical signals for sequences of rising and falling edges to determine or estimate the angular velocity and/or direction of rotation of the rotatable component.
However, many encoders are not suitable for use within the constrained proportions of an electronic device having a small form factor. As one example, smaller light sources may emit less light, smaller optical sensors may detect less light, and smaller rotatable components with patterned surfaces may be more difficult and/or expensive to manufacture. Furthermore, as angular velocity increases, the contrast of the light reflected by the patterned surface and collected by the optical sensor can decrease. As a result, the accuracy, precision, and/or reliability of angular velocity measurements derived from the optical sensor data can decrease with the size of the rotary encoder. In other examples, small form factor rotary encoders may be limited to low-speed operation.
Accordingly, there may be a present need for an improved rotary encoder suitable for inclusion within small form factor devices.